The present invention relates generally to medical catheters, such as gastrostomy feeding tubes, and relates more particularly to low profile adaptors well-suited for use with medical catheters.
Certain patients are unable to take food transorally due to an inability to swallow. Such an inability to swallow may be due to a variety of reasons, such as esophageal cancer, neurological impairment and the like. Although the intravenous administration of food to such patients may be a viable short-term approach, it is not well-suited for the long-term. Accordingly, the most common approach to the long-term feeding of such patients involves gastrostomy, i.e., the creation of a feeding tract or stoma between the stomach and the upper abdominal wall. Feeding is then typically performed by administering food through a feeding tube that has been inserted into the feeding tract, with the distal end of the feeding tube extending into the stomach and being retained therein by an internal anchor or bolster and the proximal end of the feeding tube extending through the abdominal wall.
Although gastrostomies were first performed surgically, most gastrostomies are now performed using percutaneous endoscopy. In one type of percutaneous endoscopic gastrostomy (PEG) technique, the distal end of an endoscope is inserted into a patient's mouth and is passed through the esophagus into the stomach. After distension of the stomach by inflation, an entry site on the abdomen is identified and an incision can be made. A needle, with an outer cannula, is inserted through the entry site across the abdominal and gastric walls. While keeping the cannula in place, the needle is then removed and a flexible wire is passed through the cannula into the stomach. A snare loop is extended from the distal end of the endoscope. The endoscopic snare loop is then used to grasp the wire, the cannula is released, and the endoscope and wire are withdrawn through the esophagus and mouth of the patient. A silicone gastrostomy feeding tube, the distal end of which is attached to a silicone, dome-shaped internal bolster, is then secured to the wire and is pulled from its proximal end through the esophagus and into the stomach until the internal bolster engages the stomach wall and the feeding tube extends through the stomach and abdominal walls, with the proximal end of the feeding tube extending approximately one foot beyond the abdominal wall. (Over a period of several days following implantation of the feeding tube, a stable stoma tract forms around the feeding tube between the gastric and abdominal walls.)
With the internal bolster in place against the gastric wall, an external bolster is typically secured to the feeding tube to engage the abdomen so as to prevent longitudinal movement of the feeding tube within the stoma tract. Additionally, a “Y-port” adapter is typically attached to the proximal end of the feeding tube, the Y-port adapter being adapted to receive a pair of connector tips through which food and/or medications may be dispensed. In addition, a detachable locking clip is typically secured to the feeding tube at a point between the external bolster and the Y-port adapter to prevent gastric fluids from escaping through the proximal end of the feeding tube when the feeding tube is not in use.
Alternative techniques for implanting gastrostomy feeding tubes using percutaneous endoscopic gastrostomy are disclosed in U.S. Pat. No. 5,112,310, inventor Grobe, which issued May 12, 1992, and U.S. Pat. No. 5,167,627, inventors Clegg et al., which issued Dec. 1, 1992, both of which are incorporated herein by reference.
Although gastrostomy feeding tubes of the type described above work well for their intended purpose, many active patients find the nearly one foot length of tubing that extends externally to be unwieldy, difficult to conceal and susceptible to being inadvertently pulled on. As can readily be appreciated, these conditions are potential sources of physical and/or psychological trauma to the patient. Consequently, a variety of low-profile replacement tube assemblies (also referred to in the art as low-profile replacement PEG devices) have been designed for implantation within the stoma tract following the removal of an initially-implanted gastrostomy feeding tube. Such replacement assemblies are referred to as being “low-profile” because they are considerably more compact externally than the above-described initially-implanted gastrostomy feeding tube assemblies.
An example of a low-profile replacement PEG device is disclosed in U.S. Pat. No. 4,944,732, inventor Russo, which issued Jul. 31, 1990, and which is incorporated herein by reference. The low-profile replacement PEG device of said patent comprises a deformable, conical tip portion having at least one side aperture therethrough, a tube portion which extends rearwardly from the tip portion, a fitting portion on the rear end of the tube portion, a removable valve portion in the fitting portion and a flange portion which extends outwardly from the fitting portion. The device is adapted to be installed in a patient so that the tube portion extends through a pre-established stoma with the tip portion located in the patient's stomach and with the fitting portion and the flange portion engaging the skin of the patient adjacent the stoma.
The deformable tip portion of the above-described low-profile replacement PEG device functions as an internal bolster to anchor its associated tube portion in a patient's stomach. To implant and/or remove the aforementioned tube portion from a patient's stomach, an obturator or similar device is typically inserted through the tube portion and is used to elongate or otherwise deform the tip portion in such a way as to permit the tip portion to fit through the stoma. Removal of the obturator from the tip portion then permits the tip portion to expand to its original shape for anchoring.
Another type of low-profile replacement PEG device uses an inflatable balloon, instead of a deformable tip portion, as an internal bolster to retain the distal end of its associated tube within a patient's stomach. To implant such a device in a patient, the inflatable balloon is deflated, the distal end of the tube portion is inserted through the stoma, and the balloon is then inflated. To remove the implanted device from a patient, the balloon is deflated and the tube is then withdrawn from the stoma.
Further examples of low-profile replacement PEG devices are disclosed in U.S. Pat. No. 4,863,438, inventors Gauderer et al., which issued Sep. 5, 1989; and U.S. Pat. No. 5,720,734, inventors Copenhaver et al., which issued Feb. 24, 1998, both of which are incorporated herein by reference.
Although low-profile replacement PEG devices are less awkward and bulky than initially-implanted gastrostomy tube assemblies, the use of such low-profile replacement PEG devices suffers from its own set of shortcomings. One such shortcoming is that the implantation of a low-profile replacement PEG device must be preceded by the removal of an initially-implanted gastrostomy tube. Such removal typically involves pulling on the proximal end of the gastrostomy tube until the internal bolster fails and is drawn through the stoma. As can readily be appreciated, such a procedure can be quite painful to the patient and can result in damage to the stoma, thereby delaying when the replacement device can be implanted.
Another shortcoming of many low-profile replacement PEG devices is that such devices typically do not last as long as initially-implanted gastrostomy tube assemblies (most commonly due to failure of their internal anchoring mechanisms or due to clogging or other failure of their valve mechanisms) and, therefore, must be replaced more frequently than is the case with initially-implanted gastrostomy tube assemblies.
Still another shortcoming of many low-profile replacement PEG devices is that such devices are typically not adjustable in length. This can be problematic because there is often an appreciable variation in stoma length from patient to patient. Consequently, it is typically necessary, after removal of the initially-implanted tube and prior to implantation of the replacement device, to measure the length of the stoma and then to select a replacement device having an appropriate length. As can readily be appreciated, this approach requires that there be made available an inventory of replacement devices of varying lengths.
In order to avoid the aforementioned shortcomings of low-profile replacement PEG devices while, at the same time, avoiding the above-described problems associated with having a gastrostomy tube extend externally for a substantial length, there have recently been devised a number of adaptors designed for use in converting an initially-implanted gastrostomy tube into a low-profile PEG device. One such adaptor is disclosed in U.S. Pat. No. 5,549,657, inventors Stern et al., which issued Aug. 27, 1996, and which is incorporated herein by reference. According to said patent, an adaptor is disclosed therein that is designed for use with a gastostomy feeding tube which has been inserted by means of conventional endsocopic procedures and which has been cut to a desired length by a surgeon. The adaptor is said to comprise an anti-reflux valve assembly having a stem which can be plugged into the open end of the feeding tube. The valve assembly is said to contain a seal which functions as a one-way valve to prevent reflux of gastric contents but which permits the introduction of feeding solution into the feeding tube. A clamp is placed around the feeding tube and the valve stem and is locked into place to secure the valve assembly to the feeding tube at a location flush with the patient's skin. A silicone cover is placed around the clamp to protect the patient from skin irritation caused by the clamp and also to protect the clamp and valve assembly from contaminants.
Although the aforementioned adaptor favorably addresses some of the problems discussed above, the present inventors have identified certain shortcomings associated therewith. One such shortcoming is that the valve assembly of the subject adaptor relies upon the use of a silicone gasket having a Y-shaped slot through which a cannula is typically inserted to deliver food and/or medications. However, such a silicone gasket, after repeated insertions of the cannula therethrough, has a tendency to tear or to otherwise fail to act reliably as a one-way valve. Consequently, because the adaptor cannot easily be disconnected from the gastrostomy feeding tube once connected thereto, replacement of a worn adaptor requires the removal and replacement of the gastrostomy tube as well.
Another shortcoming with the aforementioned adaptor is that it possesses a relatively small lumen through which fluid may pass. In addition, due to its manner of operation, the valve tends to get clogged over time, further restricting fluid flow.
Still another shortcoming with the aforementioned adaptor is that the clamp of said adaptor has a tendency to pinch the proximal end of the gastrostomy tube at those points where the male and female sections of the clamp are joined. Such pinching, over time, has a tendency to cause the tube to tear.